COST is an intergovernmental framework for European Cooperation in Science and Technology, allowing the coordination of nationally-funded research on a European level. Part of COST was COST Action C26 ‘Urban Habitat Constructions Under Catastrophic Events’, which started in 2006 and held its final conference in Naples, Italy, on 16-18 September 2010. The participation of 23 European countries confi rmed the international interest of COST Action C26. The main objective of COST Action C26 was to increase the knowledge of the behaviour of constructions in urban habitat under catastrophic events (earthquakes, fi re, wind, impact, explosions etc.), in order to predict their response when both the applied loading and the inherent structural resistance are combined in such a way that the safety level reaches unacceptable values, leading in some cases to a premature collapse.The activity of COST C26 Action was developed by four Working Groups (WGs), each dealing with the main issues related to catastrophic events: WG 1 “Fire resistance”; WG 2 “Earthquake resistance”; WG3 “Impact and explosion resistance”; WG 4 “Risk assessment for catastrophic scenarios in urban areas”. In addition, an “ad hoc” Working Group on “Lexicon” was created. The Final Report represents the results of the COST C26 Action, summarized in fi ve chapters: (I) Characterization of catastrophic actions on constructions; (II) Analysis of behaviour of constructions under catastrophic events; (III) Evaluation of vulnerability of constructions; (IV) Protecting, strengthening and repairing; (V) Strategy and guidelines for damage prevention, where each WG contributed to its specifi c subject.This Final Report of COST Action C26 Urban Habitat Constructions Under Catastrophic Events will be of interest to academics and engineers in civil and structural engineering, especially those involved in fire resistance, earthquake resistance,impact and explosion resistance, and resistance to Infrequent Loading Conditions.